This invention relates to a method and apparatus for controlling a shot-peening device, and, more particularly, to maximizing an impact of a collision of a stream of shot particles to be projected from a nozzle.
In one conventional use of shot peening, a stream of shot, i.e., particles, is directed from a nozzle to the surface of a workpiece such that a collision occurs thereon. Although the impact of the collision of the stream of the shot particles can be readily controlled to be a suitable value that is needed for the workpiece, it is difficult to set such an impact for the optimal and most efficient conditions. Further, an approach to achieve such optimal and most efficient conditions of the impact causes the consumption of the energy for the shot-peening process to increase relatively.
Accordingly, there exists a need in the art for a method and apparatus for shot peening that maximizes the impact of a stream of shot, that is accurate, and that has a low consumption of energy.
Therefore, one object of the invention provides a method for controlling a shot-peening device having an enclosure in which are located a workpiece to be shot peened and at least one nozzle for projecting shot particles and for directing them onto the workpiece under specified conditions for projecting the shot particles. The conditions for projecting the shot particles are partly defined by a shot-peening process to be applied to the workpiece. The method comprises steps a) through g).
First, step a) is to acquire data for maximizing the anticipated shot-peening intensity at the workpiece based on the predetermined conditions for projecting the shot particles.
In step b), a shot-peening process to be applied to the workpiece is then selected.
In step c), the conditions for projecting the shot particles to maximize the anticipated shot-peening intensity at the workpiece are then determined based on the acquired data and the selected shot-peening process before the shot particles have been actually projected.
In step d), the shot particles are then projected and directed onto the workpiece from the nozzle under the determined conditions for projecting the shot particles.
In step e), the shot-peening intensity at the workpiece is then measured based on the actually projected shot particles.
In step f), at least some of the present conditions for projecting the shot particles to maximize the measured shot-peening intensity are controlled based on the acquired data.
In step g), the shot particles are projected and directed onto the workpiece from the nozzle under the controlled conditions for projecting the shot particles.
To increase the accuracy of the shot-peening process, steps e) through g) may be repeated a plurality of times after step g) is completed.
In one aspect of the invention, at least some of the conditions for projecting the shot particles include the mass-flow rate of the shot particles to be fed to the nozzle, and the pressure or flow rate of the compressed air to be used to project the shot particles from the nozzle.
As used herein, the term mass-flow rate of the shot particles refers to the flow rate of the mass of the shot particles.
Another object of the invention is to provide an apparatus for controlling a shot-peening device having an enclosure in which are located a support for supporting a target to be shot peened and at least one nozzle for projecting shot particles and for directing them onto the target under conditions for projecting the shot particles. The conditions for projecting the shot particles are partly defined by a shot-peening process to be applied to the target.
The apparatus comprises a) measuring means for measuring the shot-peening intensity by the actually projected shot particles at a position for measuring which is located at or near the target within the enclosure; b) storing means for storing data for maximizing the anticipated shot-peening intensity at the position for measuring based on the predetermined conditions for projecting the shot particles; means for determining the conditions for projecting the shot particles to maximize an anticipated shot-peening intensity at the position for measuring based on the stored data from the memory and a selected shot-peening process before the shot particles have been actually projected; means for operating the nozzle such that the nozzle projects the shot particles and directs them onto the target therefrom under the determined conditions for the operation thereof, and e) controlling means for controlling at least some of the present conditions for projecting the shot particles to maximize the measured shot-peening intensity based on the acquired data such that the nozzle projects the shot particles and directs them onto the target therefrom under the controlled conditions thereof.
In the embodiment of the invention the measuring means includes a sensor for sensing the kinetic energy or its equivalent of the actually projected shot particles at the position for measuring and for sending a sensing signal, and means for converting the sensing signal of the sensor into the corresponding shot-peening intensity.
The sensor may be located in the support near the target. In this case, the target is a workpiece to be shot peened.
Alternatively, the target may be a dummy workpiece in which the sensor is located.